Fix binding __webglFramebuffer when mipmaps are used

Closes mrdoob#30745

Author: haxiomic

Diff for: src/renderers/webgl/WebGLTextures.js

@@ -1629,7 +1629,17 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 			if ( isCube ) throw new Error( 'target.depthTexture not supported in Cube render targets' );
 
-			setupDepthTexture( renderTargetProperties.__webglFramebuffer, renderTarget );
+			const mipmaps = renderTarget.texture.mipmaps;
+
+			if (mipmaps && mipmaps.length > 0) {
+
+				setupDepthTexture( renderTargetProperties.__webglFramebuffer[0], renderTarget );
+
+			} else {
+
+				setupDepthTexture( renderTargetProperties.__webglFramebuffer, renderTarget );
+
+			}
 
 		} else {
 
@@ -1660,7 +1670,17 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 			} else {
 
-				state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );
+				const mipmaps = renderTarget.texture.mipmaps;
+
+				if (mipmaps && mipmaps.length > 0) {
+
+					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer[0] );
+
+				} else {
+
+					state.bindFramebuffer( _gl.FRAMEBUFFER, renderTargetProperties.__webglFramebuffer );
+
+				}
 
 				if ( renderTargetProperties.__webglDepthbuffer === undefined ) {